Many proposals have been made for enhancing the spark produced by a spark plug in an internal combustion engine by providing one or more secondary or auxiliary spark gaps in the electrical circuit leading to the primary or firing gap of the plug. Among the disclosures of auxiliary spark gaps of this type are U.S. Pat. Nos. Re. 14,957; 738,922; 1,093,744; 1,164,082; 1,200,663; 1,423,219; 1,518,248; 1,729,576; 1,893,204; and 2,260,399. It has been found that use of an auxiliary or secondary gap increases the intensity of the spark produced by the spark plug, thereby tending to overcome the adverse effects of carbon or oil which may exist in the vicinity of the firing gap of the spark plug. Accordingly, the spark plug fires more reliably, resulting in improved economy, smoother running, easier starting, and increased spark plug life.
In the devices heretofore known, a wide variety of arrangements for producing the secondary spark has been employed, including spaced pointed electrodes providing an air gap, flat opposed electrodes separated by a solid or perforated mass of dielectric material, individual washers of dielectric material, and various combinations thereof. In the cases where a dielectric material is used to separate the opposed electrodes between which the secondary spark is produced, it has been proposed to use porcelain, mica, glass or similar dielectric material which has a high resistance to the flow of electricity and which can withstand the localized high temperatures produced by the spark which is created.
In accordance with the invention, there is provided a spark enhancer, which in one embodiment is built integrally into a conventional spark plug, and in another embodiment is adapted to be inserted in the high tension line leading from the distributor or ignition coil to the spark plug, in which a novel, superior dielectric material is used in place of the materials heretofore used for this purpose. Specifically, it has been found that marine shells, i.e., the hard outer shells of marine animals such as marine snails and bivalves, possess an unexpectedly superior combination of properties for use as the separation insulators between the electrodes forming the secondary spark gap. Marine shells of this type are resistant to high temperatures, they are sufficiently electrically non-conductive to permit a spark to be formed between two electrodes separated by and in contact with the shell, and they appear to be electrically conducting to a small extent, sufficient to modify the spark which is formed in a manner which produces superior results, when compared with other dielectric materials which have been used for the same purpose.